The invention refers to a pressurized container, such as a hand-operated spray can, preferably for holding gaseous propelled liquids such as chemical reaction mixtures like foams, as well as a method for filling the pressurized container.
On a face that closes the pot-shaped jacket with an integrated base a valve disk closes an open end, such pressurized cans have a hand-operable valve for a regulated, metered release of the contents.
Such faces used as valve disks arc normally made of sheet metal that is crimped on the inside around the circumference with the free end of the jacket of the pressurized container by joint plastic deformation. Additional crimping is carried out between the axially jacket-shaped hole of the valve disk and the valve housing that is attached coaxially therein.
A drawback of such crimped pressurized cans, to which this invention refers, is that occasional leaks develop. Moreover, due to the fact that the seal between the face and the jacket frequently acts only along a line, an increased pressure loss occurs because of interfacial diffusion, as a result of which the storage time prior to use of the product is limited. Due to alternating mechanical stress, the actuation of the valve during the filling and by the user additionally causes a reduction or loss of the seal that acts only along a line.
Therefore, with such pressurized cans, resin materials are used as sealing compounds which cover the two surfaces that are joined by the crimping and which seal on at least one side of the resulting total surface in a gas-tight manner. The resin material is normally inserted into the pressurized can when it is filled, whereby the surface of the pressurized can that is to be scaled is oriented downwards. This process, however, can only be used when the gaseous propellant is air.
The object of the invention is to provide a technologically simple embodiment of a pressurized container and an associated method which considerably reduces leaking and/or the pressure loss in pressurized containers.
Essentially, in the case of a pressurized container with crimped surfaces, the contact regions, at least partially, have a gas-tight sealing compound as an intermediate layer between the two surfaces. For this purpose, a gas-tight sealing compound is inserted into the pressurized container before the crimping.
The intermediate layer of the gas-tight sealing compound always forms a surface-covering seal between the two crimped surfaces that are to be sealed. Moreover, a bead that protrudes on both sides relative to the resulting surface acts as a mechanical support in case of mechanical stress, especially of the valve. This is particularly advantageous during the filling process and during the utilization.
The gas-tight sealing compound that has not yet cured is advantageously thixotropically flowable, as a result of which it does not drip.
Advantageously, the pressurized can is heated up after the scaling compound has been inserted.
Preferably, the crimping is carried out only after the sealing compound has at least partially cured.
Advantageously, the gas-tight sealing compound cures over time by meant of a chemical reaction that takes place with the gas that is present as the propellant and/or with the liquid contents.
Preferably, the gas-tight sealing compound is a cross-linkable, end-elastic reaction resin.
The method of filling takes place essentially as follows:
1. Application of the flowable gas-tight scaling compound on at least one region or one of the surfaces of the pressurized can that face each other during the crimping.
2. Optional heating of the pressurized can in order to accelerate the curing process.
3. Optional waiting for a time needed for at least partial curing.
4. Crimping of the surfaces.
5. Filling of the pressurized can with its contents.